No abstract

: Many human augmentation devices have been developed in the past few decades, but lots of them neglected the importance of well-timed assistance, which commonly leads to problems like lowered performance or interference with user's movement. In this research the authors focused in depth on the timing issue of powered assistance. As a pilot study for the proof of concept, the authors hypothesized that different timing of assistance may greatly affect the efficiency of movement for power-assisting devices, and verified the hypothesis through human experiment on sit-to-stand (STS) movement. By measuring the electromyogram (EMG) of lower limb muscles, the authors firstly confirmed the effectiveness of assistance, then compared the effect of assistance timing with other frequently investigated determinants of STS movement, and evaluated the efficiency of movement under different timing conditions. The results demonstrated the importance of timing in powered assistance, and showed that, rather than the common practice of providing assistance after the onset of movement, which is adopted by most traditional proportional-EMG-controlled human augmentation devices, it may improve the efficiency of movement for at least half of the subjects simply by adopting an earlier (before or at the same time of movement onset) but optimal timing for assistance. As a preparation for future works, the authors also quantitatively analyzed various early timing conditions, and the result indicated that if the authors could realize appropriate movement prediction mechanism, the performance of assistance may be improved further. Considering the generality of timing issue in many related works, these results could lead to a new direction of research on performance improvement of human augmentation devices.